Natural gas dehydrator and system

ABSTRACT

An improved apparatus and method for use with a natural gas dehydrator. The apparatus and method of the invention provide for recirculation of gaseous or combustible materials so that they are not released into the atmosphere and to provide fuel for the process. Likewise, liquid hydrocarbons are collected. Various components, including separators, an absorber, wet glycol, dry glycol, an effluent condenser, heat exchangers, and a reboiler are utilized in accordance with the present invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of U.S. patentapplication Ser. No. 10/071,721, entitled “Apparatus for Use with aNatural Gas Dehydrator”, to Heath, filed on Feb. 8, 2002 now U.S. Pat.No. 6,551,379, and the specification thereof is incorporated herein byreference. This application is also related to U.S. Pat. No. 5,766,313,entitled “Hydrocarbon Recovery System,” to Heath; U.S. Pat. No.6,238,461, entitled “Natural Gas Dehydrator,” to Heath; and U.S. Pat.No. 6,364,933, entitled “Apparatus for Use with a Natural GasDehydrator,” to Heath; and the specifications thereof are incorporatedherein by reference.

This application claims the benefit of the filing of U.S. ProvisionalPatent Application Ser. No. 60/377,259, entitled “Apparatus for Use WithNatural Gas Dehydrator”, filed on Apr. 30, 2002, and the specificationthereof is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention (Technical Field)

The present invention relates generally to an apparatus and system foruse with natural gas dehydrators of the type used to remove water andwater vapor from a natural gas stream having a mixture of natural gas,liquid hydrocarbons, liquid hydrocarbon vapors, water and water vapors.The invention is particularly directed for use in the regulation of theglycol and the processing of all combustible gases with natural gasdehydrators.

2. Description of Related Art

Note that the following discussion refers to a number of publications byauthor(s) and year of publication, and that due to recent publicationdates certain publications are not to be considered as prior artvis-a-vis the present invention. Discussion of such publications hereinis given for more complete background and is not to be construed as anadmission that such publications are prior art for patentabilitydetermination purposes.

An example of natural gas dehydrators is disclosed in U.S. Pat. No.6,238,461 issued May 29, 2001 and U.S. Pat. No. 6,364,933 issued Apr. 2,2002 to Heath and the disclosures therein are specifically incorporatedherein by reference. In general, such systems comprise a separator forreceiving oil and water liquids from “wet” (water vapor laden) gas; anda water absorber, which employs a liquid dehydrating agent such asglycol, for removing the water vapor from the wet gas and producing“dry” gas suitable for commercial usage. The glycol is continuouslysupplied by a pump to the absorber in a “dry” low-water vapor-pressurecondition and is removed from the absorber in a “wet” high-watervapor-pressure condition. The wet glycol is continuously removed fromthe absorber and circulated through a reboiler, which includes a stillcolumn for removing the absorbed water from the glycol and heating theglycol to provide a new supply of hot dry glycol. Heating of the glycolin the reboiler is generally accomplished through use of a gas burnermounted in a fire tube. The hot dry glycol from the reboiler passesthrough a heat exchanger, where the hot dry glycol transfers some of itsheat to incoming wet glycol going to the still column. The dry glycolsubsequently passes to a dry glycol storage tank. A glycol passage isprovided to enable passage of wet glycol from the absorber to thereboiler and to pump dry glycol from a storage tank to the absorber.Besides water, the wet glycol going to the still column of the reboilerof the natural gas dehydrator will contain natural gas and absorbedhydrocarbons, and other gaseous components.

On many dehydrators, a volume of natural gas is intentionally inducedinto the reboiler in order to dry the wet glycol to a higherconcentration than can be accomplished by simply adding heat. Theprocess of intentionally inducing a volume of natural gas into thereboiler is referred to as gas stripping.

In the still column of the reboiler of the natural gas dehydrator, thewater, natural gas, and other hydrocarbons are separated from the glycolby the pressure reduction from the absorber pressure to approximatelyatmospheric pressure in the still column and by the application of heatto the reboiler.

The water, natural gas, other hydrocarbons and gases contained in thewet glycol stream which are separated in the still column from the wetglycol are exhausted as vapors into the atmosphere through theatmospheric vent on the still column unless facilities are installed tocollect and dispose of the vented vapors. The hydrocarbon vaporsreleased through the still column of a natural gas dehydrator are airpollutants. Specifically, certain hydrocarbons such as benzene, toluene,ethylbenzene, and xylene, commonly referred to as BTEX have been provento be carcinogenic. Other gases such as hydrogen sulfide, when present,are toxic.

The gas dehydrator and systems for use with gas dehydrators disclosed inU.S. Pat. Nos. 6,238,461, 5,766,313, 6,364,933, and Ser. No. 10/071,721offer solutions to at least some of the problems discussed above. Thepresent invention provides improvements to such gas dehydrators andsystems.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to an apparatus for use with a natural gasdehydrator, and gas dehydrator systems. The preferred apparatus, methodand system of the invention preferably comprises an absorber, wetglycol, dry glycol, a glycol-to-glycol heat exchanger, at least oneseparator apparatus, a reboiler, a condenser, and at least onecirculating apparatus for wet glycol, dry glycol, gaseous hydrocarbons,and liquid hydrocarbons. Preferably, all gaseous hydrocarbons arecirculated via the circulating apparatus to the reboiler and are notreleased to the atmosphere. Likewise, preferably all liquid hydrocarbonsare collected.

A primary object of the present invention is to provide an improved andefficient system for use with a gas dehydrator.

A primary advantage of the present invention is that it is easy tooperate and does not release combustible gases into the atmosphere.

Other objects, advantages and novel features, and further scope ofapplicability of the present invention will be set forth in part in thedetailed description to follow, taken in conjunction with theaccompanying drawings, and in part will become apparent to those skilledin the art upon examination of the following, or may be learned bypractice of the invention. The objects and advantages of the inventionmay be realized and attained by means of the instrumentalities andcombinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the specification, illustrate one or more embodiments of the presentinvention and, together with the description, serve to explain theprinciples of the invention. The drawings are only for the purpose ofillustrating one or more preferred embodiments of the invention and arenot to be construed as limiting the invention. In the drawings:

FIG. 1 is a flow diagram of one embodiment of the invention;

FIG. 2 is a flow diagram of another embodiment of this invention;

FIG. 3 is a flow diagram of another embodiment of this invention;

FIG. 4 is a sketch of a water exhauster of this invention;

FIG. 5 is a sketch of a blowcase of this invention;

FIG. 6 is a flow diagram of another embodiment of this invention;

FIG. 7 is a sketch of a hydrocarbon gas stripping system of thisinvention;

FIG. 8 is a flow diagram of another embodiment of this invention;

FIG. 9 is a sketch of a glycol storage and glycol reservoir of thisinvention; and

FIG. 10 is a flow diagram of another embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is an apparatus and system for use with a naturalgas dehydrator. The gas dehydrator and systems disclosed in U.S. Pat.Nos. 5,766,313, 6,238,461, 6,364,933, and Ser. No. 10/071,721 are usefulin understanding the present invention and the disclosures arespecifically incorporated herein by reference.

The volume and pressure of the natural gas flowing through the system ofthe present invention can vary in wide ranges. Each unit is designed bythose skilled in the art to perform at wide ranges of volume andpressure of the natural gas being processed and various controls havebeen associated with the natural gas dehydrators so that thesedehydrators can be operated in a conventional manner by those skilled inthe art. The operation of the various components of this invention usesconventional apparatuses that are normally used in the operation of anatural gas dehydrator. Therefore, the specific parameters associatedwith the operation of the various components of this invention areparameters known by those skilled in the art.

As shown in the drawings, in accordance with the present invention, thenatural gas is first passed through conventional two or three-phaseinlet separator 3 to remove water and liquid hydrocarbons therefrom. Thenatural gas is then fed into absorber 2, through inlet 4, so that thenatural gas can flow upwardly through absorber 2. Dry glycol isintroduced through inlet 6 and flows through spaced apart bubble traysor other contact medium (not shown) in absorber 2 and then downwardlythrough absorber 2. The dry glycol functions primarily to remove waterfrom the natural gas and becomes wet glycol. The treated natural gasexits through outlet 8 in the top portion of absorber 2 and is passedthrough tube side 9 of glycol-gas heat exchanger 10 and passes out asdry, saleable natural gas through pipe 12 at relatively high pressures,for example 50 PSIG to 1500 PSIG depending on the operating pressures ofthe pipeline system. It is understood that any type of conventional heatexchanger can be used in place of exchanger 10 illustrated in FIG. 1.

In one configuration of the invention (see FIG. 1), the wet glycol iscollected in wet glycol sump 14 in the bottom portion of absorber 2 andcontains entrained and absorbed gases, liquid hydrocarbons, and waterand exits absorber 2 at point 16, is discharged by control valve 17through filter 19 in pipe 18 to inlet 20 of reflux coil 22 located instill column 24 (explained below). The flow of the wet glycol iscontrolled by a throttling liquid level control (not shown) located inabsorber 2 and operates motor valve 17 to maintain a constant level ofwet glycol in the bottom of absorber 2. The wet glycol flows throughreflux coil 22, cooling and condensing some of the hot vapors in the topof still column 24. The wet glycol at inlet 20 is between approximately90° and 120° F. and at exit 26 is approximately 150° F. The wet glycolexits reflux coil 22 at exit 26 and flows through pipe 28 where at point30 it is combined with other wet glycol (explained below) flowingthrough pipe 32. A by-pass can be provided to by-pass reflux coil 22when desired. The combined wet glycol flows through pipe 34 and entersinlet 36 of wet glycol cooler 38. Glycol cooler 38 may be one of manytypes of coolers. As shown in the drawings, the combined wet glycolflows through a radiator and is cooled by air pushed through theradiator by a fan. Preferably, the fan is driven at a constant speed andthe amount of the cooling air passing through the radiator is controlledby a plurality of pivotally mounted shutters moved by suitable means,such as an air cylinder or other devices such as a servo motor whichmoves a rack to rotate each of the shutters between opened and closedpositions such as that marketed by AIR-X-CHANGERS as MODEL 48H. In thesystem illustrated in FIG. 1, the combined wet glycol exits the wetglycol cooler at a temperature of between approximately 90° and 120° F.

The cooled combined wet glycol exits the glycol cooler 38 and flowsthrough pipe 40 into inlet 42 of a three-phase emissions separatorapparatus 50. Free gaseous hydrocarbons contained in the wet glycol arereleased in the three-phase emissions separator apparatus 50 as a resultof the reduction of pressure from the pressure of the absorber ofbetween approximately 50 and 1500 PSIG to the pressure in thethree-phase emissions separator which is between approximately 10 and 30PSIG and preferably about 15 PSIG. Liquid hydrocarbons are separatedfrom the combined wet glycol in the three-phase emissions separatorapparatus 50 by a weir system or interface liquid level controller (notshown) and are withdrawn through outlet 52 and flow through controlvalve 54 and pipe 55 to storage (not shown) or other apparatus. Theamount of the wet glycol from the combined wet glycol entering theemissions separator 50, after the gases and liquid hydrocarbons havebeen removed, is then combined with a fixed volume of wet glycolcontained in the emissions separator 50. The fixed volume of wet glycolis continuously recirculated. Therefore, the total volume of wet glycolin the emissions separator may be described as at least two portions ofwet glycol. One portion is that required to be continuously circulatedthrough one type of apparatus as explained below and another portion tobe passed through glycol-to-glycol heat exchanger 64 for heat exchangewith the hot dry glycol exiting the reboiler as explained below. Fromthe glycol-to-glycol heat exchanger the heated wet glycol flows to thestill column and into the reboiler. The volume of wet glycol exitingemissions separator 50 to enter the glycol-to-glycol heat exchanger 64is about the same volume as the volume of glycol being pumped intoabsorber 2 by glycol pump 76 (see FIG. 1). The volume of dry glycolpumped is usually in the range of 3 to 6 gallons of dry glycol for eachpound of water removed from the gas stream. The amount of dry glycolpumped is determined in a conventional manner known to those skilled inthe art. The volume of wet glycol flowing out of emissions separator 50to the glycol-to-glycol heat exchanger 64 is controlled by control valve53 which is controlled by a throttling liquid level control (not shown)located in emission separator 50.

The freed gaseous hydrocarbons exit through outlet 56 in the top portionof the three-phase emissions separator apparatus 50 and flow throughpipe 58 into a system, such as that described in the U.S. Pat. No.5,766,313, to be used as fuel in a reboiler as described therein.

Another portion of wet glycol passes from three-phase emissionsseparator 50 through pipe 60 and enters tube side 62 of glycol-to-glycolheat exchanger 64. It is understood that any type of heat exchanger maybe used in place of the heat exchanger 64 shown in FIG. 1. Anotherportion of wet glycol in glycol-to-glycol heat exchanger 64 is heated bythe hot dry glycol therein and flows from glycol-to-glycol heatexchanger 64 through pipe 66 and enters still column 24 of conventionalreboiler 68, such as that illustrated in the '313 Patent. Anotherportion of wet glycol is changed into hot dry glycol which is then fedthrough pipe 70 into glycol-to-glycol heat exchanger 64 and is cooled bythe other portion of wet glycol. The partially cooled dry glycol thenpasses through pipe 72 into dry glycol storage tank 74 from which it ispumped by pump 76 through pipe 78 into the gas to glycol heat exchanger10 to be further cooled by the natural gas flowing through heatexchanger 10 and into pipe 12.

The one portion of the wet glycol in emissions separator 50 exitsthrough pipe 86 and enters pump 88. The one portion of wet glycolexiting from pump 88 separates at point 90 into the first stream of wetglycol flowing through pipe 92 and a second stream of wet glycol flowingthrough pipe 94. The wet glycol in pipe 94 passes through filter 96 andthen through pipe 98 into effluent condenser 84. As described above, thesecond stream of wet glycol exits effluent condenser 84 through pipe 32and is combined at point 30 with the wet glycol in pipe 28.

In a second configuration of the invention, as shown in FIG. 2, the wetglycol is collected in wet glycol sump 14 in the bottom portion ofabsorber 2 and contains entrained and absorbed gases, liquidhydrocarbons and water and exits absorber 2 at point 16. It isdischarged by control valve 17 through filter 19 in pipe 18 to point 30where the wet glycol from absorber 2 combines with cooled wetcirculating glycol from glycol cooler 38 (explained below). The flow ofthe wet glycol from absorber 2 is controlled by a throttling liquidlevel control (not shown) located in absorber 2 and operates controlvalve 17 to maintain a constant level of wet glycol in the bottom ofabsorber 2. The combined wet glycol flows through pipe 41 into inlet 42of three-phased emissions separator apparatus 50. Free gaseoushydrocarbons contained in the wet glycol from absorber 2 are released inthree-phased emissions separator 50 as a result of the reduction ofpressure from the pressure of the absorber of between 50 and 1500 PSIGto the pressure in three-phased emissions separator 50 which is between10 and 30 PSIG and preferably about 15 PSIG. Liquid hydrocarbons areseparated from the wet glycol in three-phased emissions separator 50 bygravity and by a weir system or an interfacing liquid level controller(not shown) and are withdrawn through outlet 52, control valve 54, andpipe 55 to storage (not shown) or other apparatus. The wet glycolentering emissions separator 50, after the gases and liquid hydrocarbonshave been removed, is then combined with a fixed volume of wet glycolcontained in emissions separator 50. The fixed volume of wet glycol iscontinuously recirculated. Therefore, the total volume of wet glycol inthe emissions separator has at least two portions of wet glycol. Oneportion is that required to be continuously circulated (explained below)and another portion is to be passed through a glycol-to-glycol heatexchanger 64 for heat exchange with the hot dry glycol exiting reboiler68 (explained below). From glycol-to-glycol heat exchanger 64 the heatedwet glycol flows to still column 24 and into reboiler 68. The volume ofwet glycol exiting emissions separator 50 through control valve 53 toenter the glycol-to-glycol heat exchanger 64 is about the same volume asthe volume of glycol being pumped into absorber 2 by the glycol pump 76(see FIG. 2). The volume of dry glycol pumped is usually in the range of3 to 6 gallons of dry glycol for each pound of water removed from thegas stream. The amount of dry glycol pumped is determined in aconventional manner known to those skilled in the art. The volume of wetglycol flowing out of emissions separator 50 to the glycol-to-glycolheat exchanger 64 is controlled by control valve 53 which is controlledby an interfacing liquid level control (not shown) located in emissionsseparator 50. To overcome any potential pressure drop, in excess of thegas pressure in emissions separator 50, which might occur below controlvalve 53 as a result of friction drop in the glycol piping,glycol-to-glycol heat exchanger, or other apparatus, valve 53 is locatedto receive glycol from the discharge of circulating pump 88 atapproximately 100 PSIG above the pressure in emissions separator 50(explained below).

The freed gaseous hydrocarbons exit through outlet 56 in the top portionof three-phased emissions separator apparatus 50 and flow through pipe58 into a system such as that described in the U.S. Pat. No. 5,766,313,to be used as fuel in a reboiler as described therein.

The other portion of wet glycol passes from three-phased emissionsseparator 50 through pipe 86, circulating pump 88, and pipe 61 to point65. At point 65, the other portion of wet glycol is split into twostreams. As described below, one stream of wet glycol flows through pipe92 to power eductor 112. The second stream of wet glycol flows throughpipe 94 to point 90 where the second steam of wet glycol splits into athird wet glycol stream and a fourth wet glycol stream. The third wetglycol stream flows through pipe 67, control valve 53, and pipe 57 andenters tube side 62 of glycol-to-glycol heat exchanger 64. It isunderstood that any type of heat exchanger may be used in place of heatexchanger 64 (Shown in FIG. 2). The third wet glycol stream inglycol-to-glycol heat exchanger 64 is heated by the hot dry glycoltherein and flows from glycol-to-glycol exchanger 64 through pipe 66 andenters still column 24 of conventional reboiler 68 such as thatillustrated in the '313 Patent wherein the other portion of wet glycolis changed into hot dry glycol which is then fed through pipe 70 intothe shell side of glycol-to-glycol heat exchanger 64 and is cooled bythe other portion of wet glycol. The partially cooled dry glycol thenpasses through pipe 72 into a dry glycol storage tank 74 from which itis pumped by pump 76 through pipe 78 into the gas to glycol heatexchanger 10 to be further cooled by the natural gas flowing throughheat exchanger 10 and into pipe 12. Dry glycol storage 74 has vent pipe75 which vents dry glycol storage 74 to the atmosphere. Pipe 75 isconnected to dry glycol storage 74 at point 77.

The fourth wet glycol stream flows at approximately 100 PSIG pressurecreated by circulating pump 88, through pipe 95, filter 96, pipe 97,fixed choke 101 and pipe 98 to enter the shell side of overheadcondenser 84. Fixed or variable choke 101 or a control valve actuated bya pressure control device can control the volume of wet glycol flowingthrough pipe 98. The temperature of the wet glycol entering the shellside of overhead condenser 84 is substantially the same as thetemperature of the wet glycol contained in emissions separator 50. Thetemperature of the wet glycol in emissions separator 50 is maintained bya thermostat, located in emissions separator 50, which opens and closesshutters on glycol cooler 38 (explained below), and the temperature ofthe glycol in emissions separator 50 is normally maintained atapproximately 90 to 120 degrees Fahrenheit. The fourth wet glycol streamflows through the shell side of overhead condenser 54 where the fourthwet glycol stream is in heat exchange relationship with the hot effluentfrom still column 24 (explained below). The fourth wet glycol streampasses from overhead condenser 84 through pipe 33 to the inlet 20 of areflux coil located in still column 24 (explained below). The fourth wetglycol stream flows through reflux coil 22 cooling and condensing someof the hot vapors in the top of still column 24. The fourth wet glycolstream exits reflux coil 22 at exit 26 and flows through pipe 29 toinlet 36 of wet glycol cooler 38. If desired, a bypass line can beprovided to bypass reflux coil 22. Glycol cooler 35 may be one of manytypes of coolers useful in accordance with the present invention. Thedrawings show the wet glycol flowing through a radiator and cooled byair pushed through the radiator by a fan. Preferably, the fan is drivenat a constant speed and the amount of the cooling air passing throughthe radiator is controlled by a plurality of pivotally mounted shuttersmoved by a suitable means, such as an air cylinder or other devices suchas a servo motor which moves a rack to rotate each of the shuttersbetween opened and closed positions such as that marketed byAIR-X-CHANGERS as model 48H. In the system illustrated in FIG. 2, cooledwet glycol stream 4 exits glycol cooler 38 at point 35 at a temperatureof between approximately 90 and 120 degrees Fahrenheit. From point 35the fourth, cooled wet glycol stream flows through pipe 37 to point 30where it combines with the wet process glycol from absorber 2 and thecombined wet glycol flows through pipe 40 to inlet 42 of emissionsseparator 50.

During the standard glycol dehydration process, gases and liquidhydrocarbons generated by the process are routinely released to theatmosphere. The gases and liquid hydrocarbons released to the atmosphereare the result of gas being entrained or absorbed in the dry glycolwhile it is contacting the natural gas in the absorber. Additional gasis entrained in the wet glycol when a pressure actuated pump is used topump the dry glycol into the absorber. The entrained and absorbed gasesand hydrocarbons are released from the wet glycol at two points in theprocess. First, most of the entrained gases are released from the wetglycol in the emissions separator by a reduction of pressure. Second,the balance of gases, liquid hydrocarbons, and water are substantiallyreleased from the wet glycol by the application of heat in the reboileras well as by stripping in the still column.

One of the goals of the process of this invention is to eliminate theatmospheric pollution and the wasting of hydrocarbon energy that nowoccurs in most glycol dehydration of natural gas. To accomplish thisgoal, the process collects all the combustible gaseous vapors and liquidhydrocarbons generated by the glycol dehydration process. The collectedcombustible vapors are sent to the burner fuel system to be used as fuelgas in heating the reboiler. The collected liquid hydrocarbons arerouted to a liquid storage and handling system.

As stated above, the other portion of wet glycol entering reboiler 68 issubjected to the heat in the reboiler and an effluent is formed in stillcolumn 24. This effluent may comprise liquid water, liquid hydrocarbons,vaporized water, gases and vaporized hydrocarbons. These effluents maybe treated in systems similar to those described in the '461 and '933Patents or by a system illustrated in FIG. 1, wherein the effluent Instill column 24 exits Into pipe 82 and passes through the tube side ofeffluent condenser 84 where it is cooled as described below. Effluentcondenser 84 may be of the type illustrated in the '461 and '933Patents. If desired, an effluent condenser such as that illustrated inFIGS. 6 and 7 of the '933 Patent may be modified so that the fansillustrated in the '933 Patent and labeled “234” and 252″ therein may becontinuously operated and not intermittently by a thermostat asdescribed therein. Instead, the control of the temperature in theeffluent condenser may be controlled by pivotally mounted shutterslocated in either the exit portion or the entrance portion of theeffluent condenser. These pivotally mounted shutters may be operatedbetween opened and closed positions by a servo motor, air cylinder, orother similar device controlled by a thermostat. As shown in FIG. 2, theeffluent passes through tube side 109 of effluent condenser 84 where itis cooled to approximately 90 to 120 degrees Fahrenheit by wet glycolentering the shell side of effluent condenser 84 via pipe 98. The cooledeffluent includes both gaseous and liquid components which are routed toseparator 102 via pipe 100. The cooled effluent exiting effluentcondenser 84 flows through pipe 100 and enters separator 102 which Issimilar to the separator shown in FIGS. 8 and 9 of the '933 Patentexcept that it is mounted In a vertical position instead of thehorizontal position.

In separator 102, the gaseous hydrocarbons are withdrawn from the upperportion of separator 102 through pipe 104; the liquid hydrocarbonscollected in separator 102 are withdrawn through pipe 108 and controlvalve 110 to the hydrocarbon storage facilities, the water is withdrawnthrough pipe 118 and control valve 121 to disposal. The first stream ofwet glycol passing through eductor 112 creates a vacuum to draw thegaseous hydrocarbons through pipe 104 and entrains the gaseoushydrocarbons in the first stream of wet glycol. The first stream of wetglycol passing through eductor 112 compresses the gaseous hydrocarbonsentrained therein to the pressure maintained in emissions separator 50and then flows through pipe 114 into emissions separator 50 wherein thegaseous hydrocarbons separate from the first stream of wet glycol andflow with the freed gaseous hydrocarbons through pipe 58 to the fuelsystem. Although other types of devices may be used to create the vacuumand compress the gases, an eductor is the preferred device to be used inthe present invention.

FIGS. 3 to 5 illustrate another embodiment of the present invention.These Figures incorporate a large part of FIG. 2 wherein the samereference numerals have been applied to corresponding parts of FIG. 2.In FIGS. 3 to 5, there is illustrated an embodiment of the inventionwherein additional water is removed from the dry glycol in pipe 70 tomake super dry glycol.

As illustrated in FIG. 3, the dry glycol in pipe 70 enters waterexhauster 120 (explained below), wherein additional water is removedfrom the dry glycol to make super dry glycol which exits water exhauster120 and flows through pipe 122 into the shell side of glycol-to-glycolheat exchanger 64 and then through pipe 72 into what is now super dryglycol storage 74. From storage 74, the super dry glycol is pumped toabsorber 2 and then completes the above described closed loop system byreturning to reboiler 68 via emissions separator 50, pipe 86,circulating pump 88, pipe 61, pipe 94, pipe 67, control valve 53, pipe57, glycol-to-glycol heat exchanger 64, and pipe 66 to still column 24.

The cooled, wet glycol exits glycol cooler 38 at point 35 and flowsthrough pipe 44 to inlet 164 of a condenser tube bundle 160 mounted inwater exhauster 120, as described below, to condense some of the vaporsin the vapor section of water exhauster 120. The condensate (mainlywater and some hydrocarbons) is transmitted to blowcase 124 through pipe126. Blowcase 124 has a weir system that separates the condensate intoits water and hydrocarbon components. Water from blowcase 124 isdischarged by control valve 178 into pipe 128 to combine at point 59with the wet glycol flowing in pipe 57. Control valve 178 is controlledby a liquid level control (not shown) mounted in water chamber 172 ofblowcase 124. Hydrocarbons from blowcase 124 (see FIG. 5) are preferablydischarged by control valve 188 through pipe 113 into hydrocarbonchamber 111 of vacuum separator 102. In some applications, thehydrocarbons are dumped directly to the hydrocarbon storage. Controlvalve 188 is controlled by a liquid level control (not shown) mounted inhydrocarbon chamber 184 of blowcase 124.

Except during the dumping cycle of blowcase 124, the pressure inblowcase 124, water exhauster 120 and reboiler 68 is the same. The equalpressure in blowcase 124, water exhauster 120 and reboiler 68 isestablished and maintained by connecting equalizing pipes 130 and 134 toinlet 136 of still column 24.

Water exhauster 120, blowcase 124 and the flow of fluids is preferablyas illustrated in FIGS. 4 and 5; however, other systems, such as thosedescribed in U.S. Pat. Nos. 3,589,984 and 4,332,643 and in the articleColdfinger by L. S. Reid may also be used in accordance with the presentinvention. As illustrated in FIG. 4, dry glycol at about 390° F. havinga glycol concentration of approximately 98.6 percent weightconcentration exits reboiler 68 through pipe 70 to water exhauster 120.Dry glycol 143 in water exhauster 120 is retained for about thirty (30)minutes and is changed, as described below, into super dry glycol thatflows over dam 145 into weir system 147 which separates any entrainedoil and the super dry glycol. Super dry glycol 148, having a glycolconcentration of about 99.8 percent weight concentration, exits waterexhauster 120 into pipe 122 and flows through the shell side of theglycol-to-glycol heat exchange 64 and thereafter flows as describedabove. Free oil 173 exits weir system 147 of water exhauster 120 throughpipe 150 and pipe 149 and enters through inlet 151, the weir section 190of blowcase 124 (explained below).

Dry glycol 143 in water exhauster 120 is maintained at approximately390° F. by thermo jet coil 153 which is connected to reboiler 68 atpoint 154. Thermo jet coil 153 continuously circulates hot dry glycolout of reboiler 68. The thermo jet utilizes a small volume of therecovered gas from emissions separator 50 flowing through a smallorifice 155 to create a flow of hot dry glycol through coil 153. The hotdry glycol flows through thermo-jet coil 153 and returns to reboiler 68through pipe 157 and enters reboiler 68 at point 159.

The cooled, wet glycol flows from outlet 35 of glycol cooler 38 throughpipe 44 to inlet 164 of water exhauster 120. The cooled, wet glycol, ata temperature of between approximately 90 to 120 degrees Fahrenheit,enters condenser tube bundle 160 at point 164 and exits at point 165.From point 165, the cooled wet glycol flows through pipe 163 to point 30where it combines with the process glycol from absorber 2, and, aspreviously described, from point 30, the cooled wet glycol flows throughpipe 41 to inlet 42 of emissions separator 50. The relatively cool wetglycol flowing through condenser tube bundle 160 cools the vapors invapor section 162. Cooling of the vapors in vapor section 162 results inthe condensation of some of the vapors in vapor section 162 changing thepartial pressure equilibrium of the various vapor components in vaporsection 162. The vapors in vapor section 162 generally include fourcomponents comprising water, glycol and condensable and non-condensablehydrocarbons. Since water has a relatively low boiling temperaturecompared to glycol, it has a greater vapor pressure than glycol and isthe largest component of the vapors in vapor section 162. Liquidscondensed from vapor section 162 are collected on collection tray 168and removed from water exhauster 120 at point 169. Condensation of thevapors and the removal of the condensed liquids from water exhauster 120continually changes the partial pressure equilibrium of the vapors invapor section 162 and causes the liquid components (glycol, water andhydrocarbons) in dry glycol 143 in water exhauster 120 to react tore-establish their percentage of the equilibrium vapor pressure in vaporsection 162. Being the largest component of the vapors in vapor section162, water is the largest component condensed and is the primarycomponent evolved from hot dry glycol 143 while re-establishing thepartial pressure equilibrium of the vapors in vapor section 162.Therefore, the body of hot dry glycol 143 in water exhauster 120 becomesincreasingly water dry so that super dry glycol flows from weir system147 into pipe 122.

The condensed liquids collected on collection tray 168 of waterexhauster 120, removed via point 169 and line 126, are routed tothree-phasing weir chamber 190 of blowcase 124. Three-phasing chamber190 separates the condensates from water exhauster 120 into water andhydrocarbon components and, through a weir system, routes the waterthrough valve 182 into water chamber 172 and the hydrocarbons throughvalve 176 into hydrocarbon chamber 184 of blowcase 124. Vent pipe 130,vent pipe 134, and vent pipe 250 equalize the pressure in waterexhauster 120, blowcase 124, dry glycol storage 74, and glycol reservoirvessel 244 with the pressure in reboiler 68 by connecting into stillcolumn 24 at point 136.

Referring to FIG. 5, when the water level in chamber 172 of blowcase 124reaches a level to actuate liquid level controller 174, a pressuresignal is sent to close normally opened valve 182 and to open normallyclosed valves 178 and 180. Closing valve 182 temporarily stops thetransfer of water from three-phasing chamber 190 into water chamber 172.Opening valve 180 allows recovered gas from emissions separator 50 toenter water chamber 172 to provide the pressure energy to partiallyevacuate water chamber 172 through water dump valve 178 and line 128.The evacuated water is mixed and entrained into the wet glycol in line57 before the wet glycol enters tube side 62 of glycol-to-glycol heatexchanger 64. When the water level lowers to a preset level, liquidlevel controller 174 vents pressure signal and valves 182, 178, and 180return to their normal positions. The gas in water chamber 172 flowsthrough normally opened valve 182 into three-phasing chamber 190. Oncethe pressure in water chamber 172 and three-phasing chamber 190equalizes, water again begins to flow from three-phasing chamber 190into water chamber 172. The power gas, which was released intothree-phasing chamber 190, passes from outlet 175 through equalizingpipes 134, and 130 into an inlet 136 of still column 24.

The operation of hydrocarbon chamber 184 mirrors the operation of waterchamber 172. Liquid level controller 181 operates the same as liquidlevel controller 174. Normally opened valve 176 operates the same asnormally opened valve 182. Normally closed valves 188 and 189 operatethe same as normally closed valves 178 and 180. The hydrocarbons dumpedthrough valve 188 are preferably transferred through pipe 113 tohydrocarbon chamber 111 of vacuum separator 102. In some applications,the hydrocarbons dumped from hydrocarbon chamber will be transferreddirectly to the oil storage facilities.

FIG. 6 discloses another embodiment of the invention. FIG. 6incorporates a large part of FIG. 2 wherein the same reference numeralshave been applied to corresponding parts of FIG. 2. In FIG. 6, there isillustrated another embodiment of the invention wherein additional wateris removed from the hot, dry glycol as the hot, dry glycol is exitingreboiler 68 through packed stripping column 237 mounted in reboiler 68.As illustrated in FIG. 6, hot, dry glycol at approximately 98.6 percentweight concentration exits reboiler 68 and flows downwardly throughpacked stripping column 237. While flowing downwardly through packedstripping column 237, the hot, dry glycol comes into intimate contactwith heated and vaporized, liquid hydrocarbon gases that are flowing up,counter flow to the hot dry glycol. While flowing in intimate contactwith the hot dry glycol, the heated, liquid hydrocarbon gases “gasstrip” additional water from the hot dry glycol, and the hot dry glycolexits, at approximately 99.8 weight concentration, from stripping column237. The super dry glycol enters pipe 70 and flows throughglycol-to-glycol heat exchanger 64 and pipe 72 into super dry glycolstorage 74. Super dry glycol storage 74 may be vented to the atmosphereor operating under a vacuum as shown in FIG. 9. From glycol storage 74,the super dry glycol is pumped to absorber 2 and completes the abovedescribed closed loop system by returning to reboiler 68 via emissionsseparator 50, circulating pump 88, pipe 61, pipe 94, pipe 67, controlvalve 53, pipe 57, glycol-to-glycol heat exchanger 64, and pipe 66 tostill column 24.

The heated, liquid hydrocarbon gases, required to strip additional waterfrom the hot dry glycol exiting reboiler 68 through packed strippingcolumn 237, flow through pipe 233 to the gas inlet of stripping column237. The heated, liquid hydrocarbon gases enter stripping column 237 andflow upwardly through the hot dry glycol and exit from the top ofstripping column 237 into reboiler 68. From reboiler 68 the heated,liquid hydrocarbon gases flow into still column 24 to mix with the othergases and water vapor contained in still column 24. The total of gasescontained in still column 24 are effluents. The effluents rise to thetop and exit still column 24 at point 27. As previously described, theeffluents flow, under a vacuum, through pipe 82, overhead condenser 84and pipe 100 into vacuum separator 102.

Overhead condenser 84 cools the effluent and most of the water. Hot,vaporized, liquid hydrocarbons, contained in the effluent, are changedfrom a vapor to a liquid phase. The effluent enters vacuum separator 102and, through the weir system of vacuum separator 102, are transferred tohydrocarbon chamber 111 of vacuum separator 102. Most of the liquidhydrocarbons transferred to hydrocarbon chamber 111 are again used in aclosed loop system (described below), to strip additional water out ofthe hot glycol flowing out of reboiler 68 through stripping column 237.

The heated, liquid hydrocarbon gases used in stripping column 237 toremove additional water from hot glycol exiting reboiler 68, areobtained by heating a portion of the hydrocarbon liquids which have beenrecovered as previously described, in hydrocarbon chamber 111 of vacuumseparator 102. Referring to FIG. 7, when the level of hydrocarbons inhydrocarbon chamber 111 reach the high level set point of snap actingliquid control 192, liquid level control 192 sends a pressure signal tothe common port of three-way pressure switch 194 such as supplied byWellmark, Inc. Three-way pressure switch 194 is actuated by anadjustable spring working against a pressure-loaded diaphragm. Thepressure to load the diaphragm of pressure switch 194 is supplied bythrottling liquid level control 196 mounted in hydrocarbon reservoirvessel 198. The throttling liquid level control 196 maintains arelatively fixed level of hydrocarbons in reservoir vessel 198 byincreasing or decreasing the pressure signal being sent to three-waypressure switch 194. As the liquid level control 196 senses the level inreservoir vessel 198 needs to be raised, it increases the pressuresignal to three-way pressure switch 194 shifting the three-way switch toopen port 202 and close port 200. When the level in reservoir vessel 198rises to the high level set point, the output of liquid level control196 decreases to where three-way pressure switch 194 reverses and port202 closes and port 200 opens.

When port 202 of three-way pressure switch 194 is opened and port 200 isclosed, any hydrocarbons being dumped from hydrocarbon chamber 111 ofvacuum vessel 102 by liquid level control 192 are routed to hydrocarbonreservoir vessel 198 through pipe 204, pipe 206, control valve 208, andpipe 210. When port 200 of three-way pressure switch 194 is opened andport 202 is closed, any hydrocarbons being dumped from the hydrocarbonchamber 111 of vacuum vessel 102 by liquid level control 192 are routedto storage (not shown) through pipe 204, pipe 212, control valve 214,and pipe 216. By only sending recovered liquid hydrocarbons to storagewhen reservoir vessel 198 is operationally full, the previouslydescribed system insures that there is always enough liquid hydrocarbonsin reservoir vessel 198 to operate the hydrocarbon stripping system.

Reservoir vessel 198 is maintained at a pressure of betweenapproximately 5 and 10 pounds lower than the pressure used to evacuatehydrocarbon chamber 111 of vacuum vessel 102. Back-pressure regulator238, which is connected to reservoir vessel 198 by line 236, is set torelieve, through pipe 240, any pressure in reservoir vessel 198 that isin excess of the high pressure set point. The gases that are releasedfrom reservoir vessel 198 flow through pipe 236, back-pressure regulator238 and pipe 130 to inlet 136 on still column 24. The vented gases flowinto still column 24 where they mix with the effluents in still column24. As previously described, the vented gases along with the othereffluents are recovered in vacuum separator 102. Pressure regulator 230is set approximately 5 pounds lower then the high pressure set point onback pressure regulator 238. When the pressure in reservoir vessel 198drops approximately 5 pounds below the high pressure set point, pressureregulator 230 begins to open and either recovered gas from emissionsseparator 50 or gas from the supply gas system flows through pipe 234,pressure regulator 230, and pipe 232 into reservoir vessel 198.Preferably, the gas passing through pressure regulator 230 to maintainthe low-pressure set point in reservoir 198 would, as shown, come fromthe recovered gas system.

The liquid hydrocarbons in reservoir vessel 198 are released into thehydrocarbon stripping system by control valve 218. Control valve 218 isoperated by pressure-stat 220 such as supplied by Kimray, Inc.Pressure-stat 220 has an adjustable spring that opposes apressure-loaded diaphragm. The diaphragm of pressure-stat 220 isconnected through line 226 to pipe 224. As the pressure rises in pipe224, the increased pressure on the diaphragm of pressure-stat 220 causespressure-stat 220 to react to decrease the pressure on the diaphragm ofcontrol valve 218. Decreasing the pressure on the diaphragm of controlvalve 218 causes control valve 218 to partially or completely close,decreasing or stopping the flow of hydrocarbons through pipe 222 andcontrol valve 218. As the pressure in pipe 224 decreases, the decreasedpressure on the diaphragm of pressure-stat 220 causes pressure-stat 220to react to increase the pressure on the diaphragm of control valve 218.Increasing the pressure on the diaphragm of control valve 218 causescontrol valve 218 to partially or completely open increasing the flow ofhydrocarbons through pipe 222 and control valve 218.

From outlet 219 of control valve 218, the recovered, liquid hydrocarbonsflow through pipe 223 to the inlet of either heat exchange coil 221mounted in reboiler 68 or a heat exchange coil mounted in an indirectheater (not shown). To heat the recovered, liquid hydrocarbons on newdehydrators, it is preferable to use heat exchange coil 221 mounted inreboiler 88. To heat the recovered, liquid hydrocarbons on retrofitteddehydrators, it is preferable to use a heat exchange coil mounted in anindirect heater (not shown). For this embodiment, the operation of a newdehydrator with a heat exchange coil mounted in the reboiler isdescribed. The recovered, liquid hydrocarbons flow through heatexchanger coil 221 which is immersed in the hot glycol contained inreboiler 68. While in heat exchange relationship with the hot glycol inreboiler 68, the recovered, liquid hydrocarbons gain heat causing therecovered, liquid hydrocarbons to vaporize and increase in pressure. Thehot, vaporized, liquid hydrocarbons exit heat exchanger coil 221 andflow through pipe 224 to fixed choke 228. Fixed choke 228 is sized topass the volume of vaporized, liquid hydrocarbons required to super dryhot glycol exiting stripping column 237 at point 235. Pressure-stat 220controls the pressure in pipe 224 as well as allowing (within limits)the pressure in pipe 224 to be raised or lowered to either increase ordecrease the volume of vaporized, liquid hydrocarbons flowing throughfixed choke 228. Pressure-stat 220 must be set to maintain the maximumpressure in pipe 224 to at least 5 psig below the minimum set pressurein hydrocarbon reservoir 198.

The hot, vaporized, liquid hydrocarbons exit fixed choke 228 and flowthrough pipe 233 to the gas inlet of stripping column 237. As describedabove, the hot, vaporized, liquid hydrocarbons flow upwardly through thepacking in stripping column 237 coming in intimate contact with the hotglycol which is flowing downwardly out of reboiler 68 through thepacking in stripping column 237. While in intimate contact with the hotglycol in stripping column 237, the hot, vaporized, liquid hydrocarbonscause additional water to be removed from hot, dry glycol exitingreboiler 68 and super dry glycol exits stripping column 237 at point 235and flow into pipe 70.

To complete the closed loop stripping system, as previously described,the hot, vaporized, liquid hydrocarbons flow through stripping column237, reboiler 68, still column 24, pipe 82, overhead condenser 84, andpipe 100 into the weir section of vacuum separator 102 where thecondensed liquid hydrocarbons are transferred into hydrocarbon chamber111. From hydrocarbon chamber 111, liquid hydrocarbons, enough to keepreservoir vessel 198 operationally full of liquid hydrocarbons, aretransferred through pipe 204, pipe 206, control valve 208, and pipe 210into reservoir 198. From reservoir 198, the liquid hydrocarbons flowthrough pipe 222, valve 218, heat exchange coil 221, pipe 224, fixedcoke 228, and pipe 233 into the hot, vaporized, liquid hydrocarbon inletof stripping column 237.

In some applications, where it is anticipated that high temperature gas(110 to 140 degrees Fahrenheit) will be encountered, it may be desirableto eliminate the hot glycol flow exiting the absorber from the glycolflow to the glycol cooler. Eliminating hot glycol from the absorberflowing through the glycol cooler significantly decreases the coolingload on the glycol cooler.

FIG. 8 discloses another embodiment of the invention which eliminatesthe hot glycol flow from the absorber combining with the glycol flow tothe glycol cooler. FIG. 8 incorporates a large part of FIG. 3 and FIG. 6wherein the same reference numerals have been applied to correspondingparts of FIG. 3 and FIG. 6. Either of the processes to obtain super dryglycol as shown by FIG. 3 or FIG. 6 are applicable for use with theembodiment shown in FIG. 8. To simplify the description of theembodiment shown by FIG. 8, the process to obtain super dry glycol, asshown in FIG. 3, has been selected for the description of the embodimentshown by FIG. 8.

As illustrated in FIG. 8, wet glycol is collected in wet glycol sump 14in the bottom portion of absorber 2 and contains entrained and absorbedgases, liquid hydrocarbons, and water and exits absorber 2 at point 16.The flow of the wet glycol is controlled by a throttling liquid levelcontrol (not shown) located in absorber 2 which operates control valve17 to maintain a constant level of wet glycol in the bottom of absorber2. The wet glycol is discharged by control valve 17 and flows throughpipe 13 to inlet 11 of three-phased flash separator 49.

Free gaseous hydrocarbons contained in the wet glycol are released inthree-phased flash separator 49 as a result of the reduction of pressurefrom the pressure of the absorber of between approximately 50 and 1500PSIG to the pressure in the three-phased flash separator which isgenerally between approximately 75 and 125 PSIG. Liquid hydrocarbons areseparated from the wet glycol in three-phased flash separator 49 by aweir system or interface liquid level control (not shown) and arewithdrawn through pipe 51, control valve 59 and pipe 79 to storage (notshown) or other apparatus. Control valve 59 is operated by a liquidlevel control (not shown) mounted in three-phase flash separator 49.

The freed gaseous hydrocarbons exit three-phased flash separator 49 andflow through pipe 81, back-pressure regulator 85, pipe 87, pressureregulator 89, and pipe 91 to point 47 where the freed gaseoushydrocarbons combine with gaseous hydrocarbons from emissions separator50 which are flowing to point 47 through pipe 45. The operation ofemissions separator 50 is explained below. From point 47, the combinedgaseous hydrocarbons flow through pipe 58 into a system such as thatdescribed in U.S. Pat. No. 5,766,313, to be used as a fuel in a reboileras described therein.

Backpressure regulator 85 maintains the minimum set pressure onthree-phased flash separator 49. Pressure regulator 89 controls themaximum set pressure on emissions separator 50. Backpressure regulator93 controls the maximum set pressure on three-phased flash separator 49.In the event the pressure in three-phased flash separator 49 builds to apoint high enough to actuate back pressure-regulator 93, the excesspressure is relieved through pipe 91, back-pressure regulator 93 andpipe 101.

Wet glycol exits three-phased flash separator 49 and flows through pipe15, particulate filter 19, pipe 31, control valve 23 and pipe 39 toinlet 20 of reflux coil 22. Control valve 23 is preferably operated byan interfacing liquid level control (not shown) mounted in three-phasedflash separator 49. Wet glycol flows through reflux coil 22 cooling andcondensing some of the hot vapors in the top of still column 24. The wetglycol at inlet 20 is between approximately 110 to 130 degreesFahrenheit and at the exits approximately 160 degrees Fahrenheit. Thewet glycol exits reflux coil 22 at exit 26 and flows through pipe 103 toinlet 63 of tube side 62 of glycol heat exchanger 64. It is understoodthat any type of heat exchanger may be used in place of glycol-to-glycolheat exchanger 64. The wet glycol flowing through tube side 62 ofglycol-to-glycol heat exchanger 64 is heated by the hot glycol thereinand flows from glycol-to-glycol heat exchanger 64 through pipe 66 andenters still column 24 of conventional reboiler 68, such as thatillustrated in the '313 Patent wherein wet glycol is changed into hot,dry glycol which is then fed through pipe 70 into water exhauster 120.Water exhauster 120 and blowcase 124 operate as previously described sothat hot, super dry glycol exits from water exhauster 120 through pipe122, enters the shell side of heat exchanger 64 and is cooled by thecool glycol flowing through tube side 62 of glycol-to-glycol heatexchanger 64. The partially cooled super dry glycol then passes throughpipe 72 into a super dry glycol storage 74 from which it is pumped bypump 76 through pipe 78 into the gas to glycol exchanger 10 to befurther cooled by natural gas flowing through heat exchanger 10 and intopipe 12. The cooled super dry glycol exits gas to glycol heat exchanger10 through pipe 6 and enters absorber 2 where it comes into contact withwet natural gas flowing through absorber 2. After the super dry glycolhas been contacted by wet natural gas, it collects as wet glycol in sump14 of absorber 2 and the closed glycol loop has been completed.

A second loop system is shown by FIG. 8. The second loop systemincorporates all the components required to recover the effluents whichexit the still column of a dehydrator. The major components in thesecond loop system are emissions separator 50, vacuum separator 102,glycol cooler 38, and overhead condenser 84.

At start up of the second loop system, all major components andassociated equipment and piping composing the second closed loop system,which require a glycol flow, are charged with glycol, and, at the sametime, a level of glycol is established in emissions separator 50. Theglycol level in emissions separator 50 remains relatively constant. Pipe119 facilitates making the original charge of glycol in the secondclosed loop glycol system. Pipe 119 is connected at point 121 todischarge pipe 78 from glycol pump 76 and at paint 123 to emissionsseparator 50. If introducing glycol into the second loop glycol systemis desired, glycol may be introduced by opening a manual valve (notshown) so that glycol can be pumped by pump 78 through pipe 78 and pipe119 into emissions separator 50.

The glycol charge in the second loop is continuously circulated fromemissions separator 50 by circulating pump 88. The glycol, at a pressureof approximately 100 PSIG higher than the pressure in emissionsseparator 50, flows through line 61 to point 65. At point 65 the glycolstream splits. The first glycol stream flows through pipe 92 andprovides energy to power eductor 112 (described below). The secondglycol stream flows from point 65 through pipe 69, particulate filter96, pipe 97, fixed choke or other control 101, and pipe 98 to inlet 107of the shell side of overhead condenser 84. Fixed choke or other control101 controls the volume of glycol that is flowing through pipe 98 intooverhead condenser 84. The second stream of glycol flows through theshell side of overhead condenser 84 and cools hot effluent from stillcolumn 24. The second stream of glycol exits overhead condenser 84 atexit 117 and flows through pipe 43 to inlet 36 of glycol cooler 38. Thedesign and function of glycol cooler 38 has been previously described.The cooled second stream of glycol exits glycol cooler 38 at point 35and flows through pipe 44 to inlet 164 of condenser tube bundle 160mounted in water exhauster 120. Condenser tube bundle 160 functions aspreviously described to cool hot vapors in the vapor section of waterexhauster 120. The second stream of glycol exits condenser tube bundle160 and flows through pipe 177 where it enters emissions separator 50 atpoint 42.

As previously described, heat applied to the wet glycol in reboiler 68releases effluents that exit from still column 24 at point 27. Frompoint 27, the effluents flow through pipe 82, overhead condenser 84, andpipe 100 into vacuum separator 102. The function of vacuum separator 102and eductor 112 has been previously described. Emissions separator 50has the same function as previously described, but since no processedglycol is being received or discharged by emissions separator 50, noautomatic control of the glycol level in emissions separator 50 isrequired nor is there any need for emissions separator 50 to bethree-phased.

The glycol storage on most glycol dehydrators operates at atmosphericpressure. A pipe 75, as shown in FIG. 2, is generally used to vent tothe atmosphere the glycol storage of a dehydrator. Pipe 75 is opened tothe atmosphere and is connected to glycol storage 74 at point 77.

Two problems are created when the glycol storage of a dehydrator isvented to the atmosphere. The first problem is that any excess glycol(more than the capacity of the storage to handle) that flows into thestorage as a result of overfilling of the dehydrator, upset of theprocess, or malfunction of the equipment will flow out of the glycolstorage through a vent line such as pipe 75. Depending upon how theinstallation of the dehydrator is designed to handle glycol storageoverfill conditions, any glycol which overfills the storage and flowsout a vent pipe such as pipe 75 could contaminate the environment. As aminimum, unless special accommodations have been made, any glycol, whichflows out pipe 75, will be wasted. The second problem that occurs whenthe glycol storage of a dehydrator is vented to the atmosphere is thatthe hot glycol in the storage is allowed to contact oxygen in the air.Oxygen in contact with hot glycol will cause degradation of the glycol.

FIG. 9 shows another embodiment of the invention. FIG. 9 incorporates alarge portion of FIG. 3 wherein the same reference numerals have beenapplied to corresponding parts of FIG. 3. In FIG. 3 there is illustratedan embodiment of the invention wherein the glycol storage operates undera vacuum to eliminate the problems of the glycol storage being vented tothe atmosphere.

As illustrated in FIG. 3, glycol storage 74 is connected to point 136 ofstill column 24 by vent pipe 246, vent pipe 250, vent pipe 134, and ventpipe 130. Still column 24 operates under a vacuum. Glycol storage 74 isalso connected to glycol reservoir 244 by vent pipe 248. Glycol storage74 is also connected to glycol reservoir 244 by glycol fill pipe 258,control valve 254 and pipe 260. Glycol reservoir 244 is connected tohigh-pressure discharge pipe 78 by pipe 272, fixed choke 268, pipe 266,control valve 262, and pipe 264. Operating glycol storage 74 in a closedloop glycol system under a vacuum eliminates the problems of hot glycolcoming into contact with air and of glycol being wasted or contaminatingthe environment.

As shown in FIG. 9, glycol storage 74 provides the glycol to the suctionof glycol pump 76 (glycol pump 76 may be a stand alone pump or it may bea pump that is internally mounted in the glycol storage). It isnecessary at all times to maintain, in glycol storage 74, a glycol leveladequate to provide the suction head to pump 76. To maintain the glycollevel in glycol storage 74, a reverse acting, interface liquid levelcontrol 255 is utilized. Liquid level control 255 puts out a pressuresignal that increases as the glycol level in glycol storage 74 lowersand decreases as the glycol level in glycol storage 74 rises. Thepressure signal from liquid level control 255 is connected to a controlvalve 254 and to a reverse acting pressure switch 256 such as a Kimray 3PGRA Throttle-Reverse Pilot. Pipe 258 connects control valve 254 toreservoir vessel 244. Pipe 260 connects control valve 254 to glycolstorage vessel 74. The lower opening diaphragm pressure (15 PSIG) ofcontrol valve 255 is adjusted by turning jackscrew 257 to compress thediaphragm spring. As the glycol level in glycol storage vessel 74lowers, the output pressure of liquid level control 255 increases. Whenthe output pressure of liquid level control 255 reaches 15 PSIG, controlvalve 254 begins to open and control valve 254 will remain open untilthe output pressure of liquid level control 254 drops below 15 PSIG.While control valve 254 is open, glycol in reservoir vessel 244 flowsthrough pipe 258, control valve 254, and pipe 260 into glycol storage 74maintaining the lower level of glycol in storage vessel 74.

As previously described, the output from liquid interface level control255 is connected to pressure switch 256 as well as control valve 254.The lower operating pressure of pressure switch 256 is set at 5 PSIG byadjustment of jackscrew 259. When a condition exists where more glycolfrom glycol-to-glycol heat exchanger 64 enters through pipe 72 intoglycol storage 74 than pump 76 is pumping to absorber 2, the glycollevel in glycol storage 74 will rise. As the glycol level in glycolstorage 74 rises, the output pressure of liquid level control 255decreases. When the output pressure of liquid level control 255 drops to5 PSIG, pressure switch 256 outputs a throttling pressure signal tocontrol valve 262 beginning the opening of control valve 262.

The downstream side of control valve 262 is connected by pipe 264 toreservoir vessel 244 at point 270. The upstream side of valve 262 isconnected by pipe 266, fixed choke 268, and pipe 272 to pump 76 highpressure (50 to 1500 PSIG) discharge pipe 78 which supplies the leanglycol to absorber 2. When control valve 262 is open, fixed choke 268controls the volume of glycol flowing to reservoir vessel 244. Fixedchoke 268 is preferably sized to allow no more the 25% of the outputvolume of pump 76 to flow from pipe 78 through valve 262 into reservoirvessel 244. As a result of allowing some of the glycol being pumped bypump 76 to be transferred to reservoir vessel 244 instead of enteringabsorber 2, the glycol overfill level in glycol storage 74 lowers.Lowering the glycol level in glycol storage 74 causes the outputpressure from liquid level control 255 to increase. When the outputpressure from liquid level control 255 again reaches 5 PSIG, pressureswitch 256 bleeds off the pressure signal to control valve 262 andcontrol valve 262 closes, stopping the flow of glycol from pipe 78 intoreservoir vessel 244.

Normal operation of glycol storage 74 is when the output of liquid levelcontrol 255 is between 5 and 15 PSIG. Opening and closing control valves254 and 262 maintains the level in glycol storage 74 at the normalcondition where adequate glycol is supplied to pump 76 and no hot glycolcontacts air, contaminates the environment, or is wasted. By usinginterfacing liquid level control 255, liquid hydrocarbons that mightenter glycol storage vessel 74, through contamination of the processglycol, will not materially change the glycol level in glycol storage74. Liquid hydrocarbons, which might enter glycol storage 74, wouldseparate and float on top of the glycol. Over time, the liquidhydrocarbons can build to a high level on top of the glycol in glycolstorage 74, and any additional liquid hydrocarbons will need to beremoved. As shown in FIG. 3, the outlet of pipe 261 is located close tothe top of glycol storage 74 and exits glycol storage 74 at point 263.The purpose of pipe 261 is to set the upper level of any liquidhydrocarbons that might collect on top of the glycol in glycol storage74. Liquid hydrocarbons that exit glycol storage 74 through outlet 263flow through pipe 265 to point 267 where the liquid hydrocarbons combinewith the liquid hydrocarbons from water exhauster 120. The combinedstream of liquid hydrocarbons flows through pipe 149 to enter at point151 into blowcase 124. As previously described, the weir system ofblowcase 124 transfers the liquid hydrocarbons into oil chamber 184.From oil chamber 184 the liquid hydrocarbons are transferred to eitherthe hydrocarbon chamber 111 of vacuum separator 102 or to storage (notshown).

There are applications where the amount of gas, recovered by thepreviously described invention, can be more than the amount of gasrequired to fire the reboiler. One example, of an application where theamount of gas recovered by the invention might be more than is requiredby the reboiler to heat the dehydration process, is at compressorstations where widely varying flow rates and temperatures of the gasbeing processed by the absorber can create conditions where excess gascan be recovered. A second example, of an application where the amountof gas recovered by the invention might be more than is required by thereboiler to heat the dehydration process, is where the composition ofthe gas being processed by absorber 2 creates unusually high BTU valuesfor the recovered gas.

In applications where the amount of gas recovered by the invention ismore than is required by the reboiler to heat the dehydration process,the excess recovered gas can be used for other purposes. Some of theother possible uses of the excess recovered gas are in a plants fuelsystem or the firing of other production equipment on the gas well orplant location.

In applications where there is no other use for excess gas recovered bythe invention, the excess gas can be consumed by increasing the heatload on the reboiler. FIG. 10 discloses another embodiment of theinvention. FIG. 10 incorporates a large portion of FIG. 3 wherein thesame reference numerals have been applied to corresponding parts of FIG.3. In FIG. 10, there is illustrated an embodiment of the inventionwhereby additional heat load, more then the heat load required by thedehydration process, can be applied to the reboiler.

To illustrate the present invention, the dehydration process utilizingthe invention's gas recovery system and water exhauster system forobtaining super dry glycol has been chosen. Any of the other dehydrationgas recovery processes previously described can be used to illustratethe present invention.

Referring to FIG. 10, the components necessary to inject water intostill column 24 are added to the flow diagram illustrated by FIG. 3.Pipe 278 is connected to outlet 276 located close to the bottom of therecovered water section created by the weir system in chamber 123 ofvacuum separator 102. Water flows from outlet 276 through pipe 278 tothe suction inlet of metering pump 282. Metering pump 282 may beelectrically or pneumatically powered and is designed to allow theoutput volume to be varied over a wide range. From the discharge ofmetering pump 282, recovered water is pumped through pipe 284 to point286. At point 286 the water pumped by metering pump 282 mixes with hotwet glycol flowing in pipe 66 from glycol-to-glycol heat exchanger 64.The mixture of water and hot wet glycol enters still column 24 at point288. Considering the firing efficiency of the fire tube in reboiler 68,each pound of water injected into still column 24 causes approximately2000 BTU of excess gas to be consumed by reboiler 68. In applicationswhere injecting the water into still column 24 is not practical, thewater can be injected directly into reboiler 68.

The injected water at point 288 converts to steam and mixes with othereffluents in still column 24. As previously described, the effluentsexit still column 24 at point 27 and flow through pipe 82, overheadcondenser 84, and pipe 100 into the weir section of vacuum separator102.

The injected water flows in a closed loop system from vacuum separator102 to still column 24 and overhead condenser 84, then back to vacuumseparator 102. While flowing through the closed loop system, theinjected water changes phase twice. The water exits vacuum separator 102as a liquid, reboiler 68 adds heat which converts the liquid to steam,and overhead condenser 84 condenses the steam back to a liquid beforethe water returns to vacuum separator 102.

The approximately 1200 BTU per pound of water that is removed fromreboiler 68 by converting the injected water to steam increases the heatload on overhead condenser 84 by an equal amount. By heat exchange withthe glycol flowing in the shell side of overhead condenser 84, heat fromthe steam is transferred to the flowing glycol. The flowing glycol exitsoverhead condenser 84 and flows through pipe 33, reflux coil 22, andpipe 29 to glycol cooler 38 where heat is removed from the flowingglycol by exhausting the heat into the atmosphere.

The preceding examples can be repeated with similar success bysubstituting the generically or specifically described components and/oroperating conditions of this invention for those used in the precedingexamples.

Although the invention has been described in detail with particularreference to these preferred embodiments, other embodiments can achievethe same results. Variations and modifications of the present inventionwill be obvious to those skilled in the art and it is intended to coverin the appended claims all such modifications and equivalents. Theentire disclosures of all references, applications, patents, andpublications cited above are hereby incorporated by reference.

1. A method of dehydrating natural gas, the method comprising the stepsof: providing an absorber for receiving the natural gas; linking theabsorber to a still column; transferring wet glycol from the absorber tothe still column; linking a reboiler to the absorber; transferring dryglycol from the reboiler to the absorber to dehydrate the natural gas;linking a glycol-to-glycol heat exchanger to and between the reboilerand the absorber; linking at least one separator to the still column toreceive effluent and remove liquid hydrocarbons and water from theeffluent for collection and removal of gaseous hydrocarbons from theeffluent; linking at least one vacuum generating component to the atleast one separator to receive gaseous hydrocarbons from the separator;linking at least one emissions separator to the at least one vacuumgenerating component to receive the wet glycol from the at least onevacuum generating component and from the absorber and to transfergaseous hydrocarbons to a firing system of the reboiler; and notreleasing gaseous hydrocarbons to the atmosphere.
 2. The method of claim1 wherein the at least one vacuum generating component comprises aneductor.
 3. The method of claim 1 wherein at least one of the at leastone separator apparatus comprises a vacuum separator.
 4. The method ofclaim 1 further comprising linking a glycol cooler to the still columnand to the at least one emissions separator.
 5. A method for use with anabsorber to dehydrate a natural gas stream comprising the steps of:transferring a first stream of wet glycol from the absorber to enter anemissions separator; transferring the first stream of wet glycol fromthe emissions separator to a heat exchanger; transferring the firststream of wet glycol from the heat exchanger to a still column;transferring a residual portion of the wet glycol from the still columnto a wet glycol cooler; and transferring the residual portion of the wetglycol from the wet glycol cooler to join the wet glycol leaving theabsorber to enter the emissions separator.
 6. The method of claim 5further comprising the step of linking at least one pump to theemissions separator to pump the wet glycol leaving the emissionsseparator.
 7. The method of claim 5 wherein the heat exchanger comprisesa glycol-to-glycol heat exchanger.
 8. The method of claim 5 furthercomprising the step of providing at least one pump to act upon the wetglycol and at least one pump to act upon dry glycol.
 9. The method ofclaim 8 wherein the at least one pump acting on the dry glycol issubmerged in the glycol acted upon by the pump.
 10. The method of claim5 further comprising transferring hydrocarbons from the emissionsseparator to a hydrocarbon recovery system or processing unit.
 11. Themethod of claim 10 wherein the recovery system or processing unitcomprises a reboiler.
 12. The method of claim 5 further comprising thesteps of: separating the first stream of wet glycol leaving theemissions separator to form a second stream of wet glycol; transferringthe second stream of wet glycol from the emissions separator to aneductor; transferring the second stream of wet glycol from the eductorto the emissions separator; separating the first stream of wet glycolafter forming the second stream of wet glycol to form a third stream ofwet glycol; transferring the third stream of wet glycol to an effluentcondenser; and transferring the third stream of wet glycol from theeffluent condenser to the still column.
 13. The method of claim 12wherein the glycol cooler comprises pivotally mounted shutters tocontrol the emission separator's temperature by opening and closing theshutters in response to temperature change.
 14. The method of claim 13further comprising providing a filter and providing a choke throughwhich the third stream of wet glycol passes before going to the effluentcondenser.
 15. The method of claim 12 further comprising the steps of:providing a vacuum separator; transferring a gaseous hydrocarbon streamfrom the vacuum separator to the eductor; transferring effluent from thereboiler to the effluent condenser; and transferring the effluent fromthe effluent condenser to the vacuum separator.
 16. The method of claim15 further providing an outlet to release water from the vacuumseparator and an outlet to release hydrocarbons from the vacuumseparator.
 17. The method of claim 15 further comprising the steps of:providing a water exhauster to receive wet glycol from the emissionsseparator and dry glycol from the reboiler; and providing a blowcase toreceive condensates from the water exhauster.
 18. The method of claim 17further comprising the steps of: transferring the wet glycol leaving thewet glycol cooler to the water exhauster; and transferring the wetglycol from the water exhauster to join the wet glycol leaving theabsorber to enter the emissions separator.
 19. The method of claim 17further comprising the steps of: transferring a condensate from thewater exhauster to the blowcase; transferring water from the blowcase tocombine with wet glycol coming from the emissions separator; andtransferring hydrocarbons from the blowcase to the vacuum separator tostabilize liquids.
 20. The method of claim 19 further comprising thestep of transferring hydrocarbons from the vacuum separator to ahydrocarbon storage.
 21. The method of claim 17 further comprising thesteps of: transferring dry glycol from the reboiler to the waterexhauster; transferring the dry glycol from the water exhauster to theheat exchanger; transferring the dry glycol from the heat exchanger to adry glycol storage; and transferring the dry glycol from the dry glycolstorage to the absorber.
 22. The method of claim 17 further comprisingthe steps of: transferring hydrocarbons from the water exhauster to joinwith a stream of hydrocarbons from the dry glycol storage to enter theblowcase; linking the water exhauster, the blowcase, and the reboilerwith equalizing hydrocarbon conduits; and transferring hydrocarbons fromthe blowcase to a hydrocarbon storage.
 23. The method of claim 17further comprising the steps of: transferring hydrocarbons from thewater exhauster to join with a stream of hydrocarbons from the drystorage tank to enter the blowcase; linking the water exhauster, theblowcase, and the reboiler with equalizing hydrocarbon conduits; andtransferring a second stream of hydrocarbons from the blowcase to thevacuum separator.
 24. The method of claim 23 wherein a closed loopglycol system is provided within which to operate the dry glycol storagetank under a vacuum and prevent the introduction of air into the closedloop glycol system.
 25. The method of claim 24 wherein providing theclosed loop glycol system comprises the steps of: connecting the dryglycol storage to the still column through a set of at least one ventpipe; connecting the dry glycol storage to the glycol reservoir with asecond set of at least one vent pipe; and connecting the dry glycolstorage to a glycol reservoir through at least one fill pipe.
 26. Themethod of claim 24 further comprising the step of connecting the glycolreservoir to a pipe conveying the dry glycol from the dry glycol storageto the absorber so that dry glycol may be transferred from the dryglycol storage to the glycol reservoir.
 27. The method of claim 17wherein the pressures in the blowcase, the water exhauster, and thereboiler are equal except when liquids are removed from the blowcase.28. The method of claim 17 further comprising the step of transferringwater from the blowcase to join with wet glycol entering the heatexchanger.
 29. The method to claim 17 further comprising the step oftransferring water from the vacuum separator to join with wet glycolleaving the heat exchanger to enter the still column.
 30. The method ofclaim 29 further comprising the step of providing a pump and controllingthe speed of the pump to control the volume of water leaving the vacuumseparator to join with the wet glycol.
 31. The method of claim 17further comprising the step of transferring water from the vacuumseparator to the reboiler.
 32. The method of claim 5 further comprisingthe steps of: transferring dry glycol from the reboiler to a waterexhauster, the water exhauster comprising a weir system; transferringthe dry glycol from the water exhauster to the heat exchanger;transferring the dry glycol from the heat exchanger to a super dryglycol storage; and transferring the dry glycol from the super dryglycol storage to the absorber.
 33. The method of claim 5 furthercomprising the steps of: providing a stripping column to strip water andhydrocarbons from the wet glycol; transferring partially dry glycol fromthe stripping column to a reboiler; transferring dry glycol from thereboiler to a water exhauster comprising a weir system; transferringsuper dry glycol from the water exhauster to the heat exchanger;transferring the super dry glycol from the heat exchanger to a super dryglycol storage; and transferring the super dry glycol from the super dryglycol storage to the absorber.
 34. The method of claim 33 furthercomprising the steps of: transferring hydrocarbons from a vacuumseparator to a reservoir vessel; and transferring hydrocarbons from thereservoir vessel to the stripping column.
 35. The method of claim 34further comprising providing a release for the hydrocarbons leaving thevacuum separator prior to entering the reservoir vessel.
 36. The methodof claim 35 wherein the release for the hydrocarbons is to a hydrocarbonstorage.
 37. The method of claim 34 wherein: the hydrocarbons sent fromthe reservoir vessel pass through a heat exchange coil; the hydrocarbonspassing from the heat exchange coil pass through a pressure regulatorprior to entering the stripping column within the reboiler; and thevolumes of hydrocarbons leaving the vacuum separator, entering thereservoir vessel, leaving the reservoir vessel, and going to hydrocarbonstorage, are controlled by a pressure switch.
 38. The method of claim 37wherein the pressure switch is controlled by at least one liquid levelcontrol.
 39. A method for use with an absorber to dehydrate a naturalgas stream comprising the steps of: connecting a phase flash separatorto an absorber; transferring wet glycol from the absorber to enter theflash separator; providing a valve to release hydrocarbons from theflash separator; transferring the wet glycol from the flash separator toa reflux coil; transferring wet glycol from the reflux coil to a heatexchanger; and transferring wet glycol from the heat exchanger to astill column.
 40. The method of claim 39 wherein the phase flashseparator comprises a three-phase flash separator.
 41. The method ofclaim 39 wherein the heat exchanger is a glycol-to-glycol heatexchanger.
 42. The method of claim 39 further comprising the step oftransferring gaseous hydrocarbons from the phase flash separator to ahydrocarbon recovery system or processing unit.
 43. The method of claim42 wherein the recovery system comprises a reboiler firing system. 44.The method of claim 42 further comprising the step of linking anemissions separator to the phase flash separator and transferringhydrocarbons from the emissions separator to combine with hydrocarbonstransferring out of the phase flash separator.
 45. The method of claim42 further comprising the steps of: linking a vacuum separator to aneductor; linking the eductor to an emissions separator; transferringhydrocarbons from the vacuum separator to the eductor; and transferringhydrocarbons from the eductor to the emissions separator.
 46. The methodof claim 45 wherein the vacuum separator is oriented horizontally. 47.The method of claim 45 wherein the vacuum separator is orientedvertically.
 48. The method of claim 45 further comprising the steps of:transferring a first stream of wet glycol from the emissions separatorto an effluent condenser; transferring the wet glycol from the effluentcondenser to a glycol cooler; transferring the wet glycol from theglycol cooler to a water exhauster; and transferring the wet glycol fromthe water exhauster to the emissions separator.
 49. The method of claim48 further comprising the step of separating the wet glycol leaving theemissions separator to form a second stream of wet glycol entering theeductor.
 50. The method of claim 48 further comprising the step ofconnecting a dry glycol storage to the emissions separator to provide aglycol charge.
 51. The method of claim 42 further comprising the step oftransferring the gaseous hydrocarbons from the emissions separator andfrom the phase flash separator to a hydrocarbon recovery system orprocessing unit.
 52. The method of claim 51 wherein the hydrocarbonrecovery system or processing unit comprises a reboiler.
 53. The methodof claim 39 further comprising the step of transferring liquidhydrocarbons from the phase flash separator to a vacuum separator. 54.An apparatus for dehydrating natural gas, said apparatus comprising: anabsorber linked to a still column, said absorber receiving the naturalgas; wet glycol flowing from said absorber to said still column; areboiler linked to said absorber; dry glycol flowing from said reboilerto said absorber to dehydrate the natural gas; a glycol-to-glycol heatexchanger linked to, and between, said reboiler and said absorber; atleast one separator linked to said still column to receive effluent andremove liquid hydrocarbons and water from said effluent for collectionand removal of gaseous hydrocarbons from said effluent; at least onevacuum generating component linked to said at least one separator toreceive gaseous hydrocarbons from said separator; at least one emissionsseparator linked to said at least one vacuum generating component toreceive said wet glycol from said at least one vacuum generatingcomponent and from said absorber and to transfer gaseous hydrocarbons toa firing system of said reboiler; and an effluent condenser linkedbetween, and to, said still column and said at least one separator; andwherein gaseous hydrocarbons are not released to the atmosphere.
 55. Theapparatus of claim 54 wherein said at least one vacuum generatingcomponent comprises an eductor.
 56. The apparatus of claim 54 wherein atleast one of said at least one separator comprises a vacuum separator.57. The apparatus of claim 54 further comprising a water exhaustercomprising a weir system, said water exhauster linked to said reboilerand to a heat exchanger.
 58. The apparatus of claim 54 furthercomprising a glycol cooler linked to said still column and to said atleast one emissions separator.
 59. The apparatus of claim 58 furthercomprising a blowcase linked to a water exhauster.
 60. The apparatus ofclaim 59 further comprising a glycol storage linked to said absorber anda glycol reservoir linked to said glycol storage.
 61. The apparatus ofclaim 60 wherein said glycol reservoir, said dry glycol storage, saidreboiler, said blowcase, and said water exhauster are connected with aplurality of equalizing conduits.
 62. The apparatus of claim 54 furthercomprising: a stripping column disposed within said reboiler; and areservoir vessel linked to said reboiler.
 63. A water exhausterapparatus for use with a natural gas dehydrator comprising: a condensertube to circulate wet glycol in and out of said water exhauster; aninlet to receive dry glycol from a reboiler; a section to hold dryglycol; a weir system to separate hydrocarbons from said dry glycol andto provide for the removal of said dry glycol and said hydrocarbons fromsaid water exhauster; an outlet to transfer hydrocarbons out of saidweir system; an outlet to transfer dry glycol out of said weir system;and an outlet to release condensed liquids from said water exhauster.64. The apparatus of claim 63 further comprising a coil to provide heatand to circulate dry glycol from said reboiler past said glycol in aglycol holding section of said water exhauster.
 65. A blowcase apparatusfor use with a natural gas dehydrator comprising: an inlet to receivecondensed liquids from a water exhauster; a weir chamber to separatecondensates; a water chamber to receive water from said weir chamber; ahydrocarbon chamber to receive hydrocarbons from said weir chamber; anda liquid level controller actuated by a level of said water in saidwater chamber to send a signal to stop said water from leaving said weirchamber and to allow gas to enter said water chamber to evacuate saidwater from said water chamber.
 66. The apparatus of claim 65 whereinwater evacuated from said water chamber is mixed with a stream of wetglycol.
 67. The apparatus of claim 65 wherein said gas in said waterchamber flows into said weir chamber until pressures in said waterchamber and in said weir chamber equalize so that said water flows fromsaid weir chamber to said water chamber, and said gas from said weirsystem is released into a gas recovery system.
 68. The apparatus ofclaim 67 wherein said gas recovery system comprises a reboiler firingsystem.
 69. The apparatus of claim 65 wherein said hydrocarbons flowinto said weir chamber until pressures in said hydrocarbon chamber andin said weir chamber equalize so that hydrocarbons flow from said weirchamber to said hydrocarbon chamber and said hydrocarbons are releasedfrom said hydrocarbon chamber.
 70. The apparatus of claim 69 whereinsaid hydrocarbons released from said hydrocarbon chamber are sent to avacuum separator.
 71. The apparatus of claim 69 wherein saidhydrocarbons released from said hydrocarbon chamber are sent to storagefacilities.
 72. The apparatus of claim 69 wherein hydrocarbons aretransferred to a gas recovery system.